1. Field of the Invention
This invention relates in general to subsea well completion equipment, and in particular to a tie-back connection apparatus for a subsea well.
2. Description of the Prior Art
One manner of completing a subsea well is to place the Christmas Tree at the subsea floor. Valves and controls will be associated with the Christmas Tree for controlling the flow of oil. The flow of oil will flow through a production riser to a production platform at the surface for treatment. The processed oil then is pumped down to a pipeline which leads to a gathering station.
A subsea Christmas Tree and its controls will be considerably more expensive than a Christmas Tree located above the surface of the water. Because of this, sometimes tie-back connections are used. With a tie-back, connection, conduit is connected into the wellhead housing at the subsea floor to extend to the surface. The conduit is capable of withstanding the well pressure, and is basically an extension of the well. The Christmas Tree will be mounted at the top of the conduit at the surface. The conduit will be supported in tension by a floating production vessel.
Tie-back connection devices are available. In some, it is necessary to rotate the conduit being stabbed into the subsea wellhead housing. This results in threading difficulties. In other cases, extensive running tools are necessary to actuate the locking of the upper conduit to the lower conduit.